TY - JOUR

T1 - Pilot Point Optimization of Mining Boundaries for Lateritic Metal Deposits

T2 - Finding the Trade-off Between Dilution and Ore Loss

AU - Dagasan, Yasin

AU - Renard, Philippe

AU - Straubhaar, Julien

AU - Erten, Oktay

AU - Topal, Erkan

PY - 2018/4/28

Y1 - 2018/4/28

N2 - Geological contacts in lateritic metal deposits (footwall topographies) often delineate the orebody boundaries. Spatial variations seen in such contacts are frequently higher than those for the metal grades of the deposit. Therefore, borehole spacing chosen based on the grade variations cannot adequately capture the geological contact variability. Consequently, models created using such boreholes cause high volumetric uncertainties in the actual and targeted ore extraction volumes, which, in turn, lead to high unplanned dilution and ore losses. In this paper, a method to design optimum ore/mining boundaries for lateritic metal deposits is presented. The proposed approach minimizes the dilution/ore losses and comprises two main steps. First, the uncertainty on the orebody boundary is represented using a set of stochastic realizations generated with a multiple-point statistics algorithm. Then, the optimal orebody boundary is determined using an optimization technique inspired by a model calibration method called Pilot Points. The pilot points represent synthetic elevation values, and they are used to construct smooth mining boundaries using the multilevel B-spline technique. The performance of a generated surface is evaluated using the expected sum of losses in each of the stochastic realizations. The simulated annealing algorithm is used to iteratively determine the pilot point values which minimize the expected losses. The results show a significant reduction in the dilution volume as compared to those obtained from the actual mining operation.

AB - Geological contacts in lateritic metal deposits (footwall topographies) often delineate the orebody boundaries. Spatial variations seen in such contacts are frequently higher than those for the metal grades of the deposit. Therefore, borehole spacing chosen based on the grade variations cannot adequately capture the geological contact variability. Consequently, models created using such boreholes cause high volumetric uncertainties in the actual and targeted ore extraction volumes, which, in turn, lead to high unplanned dilution and ore losses. In this paper, a method to design optimum ore/mining boundaries for lateritic metal deposits is presented. The proposed approach minimizes the dilution/ore losses and comprises two main steps. First, the uncertainty on the orebody boundary is represented using a set of stochastic realizations generated with a multiple-point statistics algorithm. Then, the optimal orebody boundary is determined using an optimization technique inspired by a model calibration method called Pilot Points. The pilot points represent synthetic elevation values, and they are used to construct smooth mining boundaries using the multilevel B-spline technique. The performance of a generated surface is evaluated using the expected sum of losses in each of the stochastic realizations. The simulated annealing algorithm is used to iteratively determine the pilot point values which minimize the expected losses. The results show a significant reduction in the dilution volume as compared to those obtained from the actual mining operation.

KW - Bauxite mining

KW - Dig limit

KW - Direct sampling

KW - Laterite simulated annealing

KW - Multiple-point statistics

KW - Optimization

UR - http://www.scopus.com/inward/record.url?scp=85046022355&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85046022355&partnerID=8YFLogxK

U2 - 10.1007/s11053-018-9380-9

DO - 10.1007/s11053-018-9380-9

M3 - Article

AN - SCOPUS:85046022355

SP - 1

EP - 19

JO - Natural Resources Research

JF - Natural Resources Research

SN - 1520-7439

ER -